Hermetically sealed switch

ABSTRACT

An hermetically impervious electrical switch of the snap action type that is enclosed in a container and is actuated by distortion of the sidewall of a tube.

United States Patent lnventor Robert R. Hellman Bridgeport, Conn.

Appl. No. 22 414 7 Filed Apr. 17, 1970 Patented Sept. 28, 1971 AssigneeWesport Development of Manufacturing Company, Inc. Milford, Conn.

HERMETICALLY SEALED SWITCH Primary ExaminerH. 0. Jones Att0rneyJohnson &Kline 7 Claims, 3 Drawing Figs.

U.S. Cl 200/168 G, 200/172 A Int. Cl H0lh 9/04 ABSTRACT: An hermeticallyimpervious electn'cal switch of Field of Search 200/168 0, the Sn p acton ype that s enclosed in a container and is actu- 172 A ated bydistortion of the sidewall of a tube.

I JJ 32 50 Q T, E 34 26 J1 76 33 35 Z7 /5 i J1 29 k/'/2 l 1 L7 I I7 I x22 /0 l I I I I I f I f I 9 l E l l i l i Z I l I $20 //a $4.9 E f I a24 2a HERMETICALLY SEALED SWITCH In my U.S. Pat. No. 3,431,378, grantedMar. 4, 1969, and assigned to the assignee of the present invention,there is disclosed a similar hermetically sealed electrical switch. Thisswitch is positioned within a sealed container and is actuated by aphysical movement against its blade to cause the blade to change, bysnap action, from engaging one contact to engaging another contact. Fortransmitting the actuating movement from outside of the container to theswitch, the container is formed with a cylindrical tube that isrelatively easily radially distortable. Thus the actuating movement istransmitted to the switch by applying a radial force against thesidewall of the tube that is in alignment with the switch blade and thetube bends along its axis to transmit the motion into the container.

While such an hermetically sealed switch has been found to beexceedingly satisfactory, the type of actuator disclosed in myabove-noted patent has been found to not be completely acceptable. Insuch a switch it is necessary that the mechanical operating points bemaintained substantially constant during use and one difficulty with theheretofore utilized actuator has been caused by the actuator beingcapable of being physically deformed when subjected to overtravelmovement. Moreover, as the actuator is required to flex to transmit themovement, attempts to increase the actuators rigidity have not beensuccessful as it increased the force required to flex the actuator inorder to actuate the switch.

It is accordingly an object of the present invention to provide anhermetically sealed electric switch in which the movement for actuatingthe switch is transmitted by distortion of a tube, but yet in which themechanical operating characteristics of the switch are maintainedsubstantially constant even over a wide range of operating conditions.

Another object of the present invention is to achieve the above objectwith an hermetically sealed switch in which there is an actuator thathas actuating portions which are substantially rigid to maintain theirdimensional characteristics but yet also have portions which are capableof easily flexing to effect transmission of the movement.

A further object of the present invention is to provide an hermeticallysealed switch which achieves the above objects and which is relativelyeconomical to manufacture and durable in use.

In carrying out the present invention, there is provided an hermeticallysealed switch similar to the electric switch disclosed in my above-notedpatent. This switch includes a snap action blade which is mechanicallymovable from its normal engagement with one contact to translate themovement into an electrical signal. The switch is mounted within aclosed container that includes a corrugated tube which has a radialportion in alignment with the switch blade such that radial distortionof this portion toward the switch blade transmits the actuating movementto effect the snap action.

In the present invention at this portion of the tube there is positioneda stud which has a head which is engageable with a ball that in turnengages the blade such that movement of the stud is directly transmittedto the blade. The shank of the stud extends through the wall of the tubeinto its interior where it is engaged by an arm that is mounted on thecontainer. The arm extends beyond one end of the tube to be engaged byan actuating link that is also secured on the exterior of the container.g'

Both the arm and the link are constructed and arranged so that they arenormally rigid in a direction for transmitting motion to the shank butyet have flexible portions which permit the motion to be transmittedwithout detriment to the parts. Accordingly, through the use of theherein disclosed actuator, the mechanical characteristics of the switchare substantially maintained even with extended overtravel movement.Moreover the arm and link are normally biased in opposition to theactuating force, thus freeing the switch blade to return to its normallyopen position when the displacement is removed from the actuator.

Other features and advantages will hereinafter appear.

Referring to the drawing:

FIG. 1 is a side view of the hermetically sealed electrical switch ofthe present invention with portions being shown in section.

FIG. 2 is a section taken on the line 2-2 of FIG. 1.

FIG. 3 is a partial section similar to FIG. 1 of a modification showinga different support for the arm.

Referring to the drawing, the snap action electrical switch of thepresent invention is generally indicated by the reference numeral 10 andincludes a body 11 on which are mounted three posts l2, l3 and 14. Thepost 12 supports one end of a contact blade 15 with its free other endcarrying a contact 16, that normally engages a normally closed contact17 carried by the post 13 and is movable to engage a normally opencontact 18 carried by the post 14, The contacts 17 and 18 arerespectively connected to lead terminals 19 and 20 while a terminal 21is connected to the contact blade 15.

A rectilinear container 22 formed from sheet metal is positioned overthe body 11 and is secured thereto by the use of a metal insert 23 whichhas an interior shape mating with the exterior periphery of a ledge 11aformed on the body. The insert 23 and the ledge are secured along theiradjoining surfaces by a hardened metal joint while a welded joint 24secures the adjacent edges of the insert 23 and the container 22. Withsuch a construction and as more specifically described in my above-notedpatent, the bottom portion of the container 22 is hermetically sealedbut yet electrical connections may be made to the contacts by use of theterminals 19, 20 and 21 that extend from the container.

In the upper portion of the container 22, forming an integral partthereof is a corrugated tube 25 which extends between the sidewalls ofthe container and is secured to each sidewall as by welded joints 26. Inthe embodiment shown in FIGS. 1 and 2, both ends of the tube are open asthe end walls of the container have circular apertures into which theends of the tube fit.

The normal position of the contact blade 15 is shown in solid lineswherein its contact 16 engages the normally closed contact 17 toelectrically connect lead 21 to lead 19. A down ward force or movementon the blade 15 will cause it to snap and move its free end fromengagement with contact 16 to engagement with contact 18 to connect lead21 to lead 20 as indicated by the dotted line position of the blade.Upon removal of the force on the blade, the natural resilience of theblade will cause it to resume its normal position.

In accordance with the present invention, the actuating force to theblade is effected by a flat head 27 of a stud 28 with the head 27engaging a ball 29 which in turn engages the blade. A shank 30 of thestud 28 extends into the interior of the tube while welding 31 serves toform a seal between the stud and the tube. As shown, the tube ispreferably formed with a flat cylindrical portion 32 for accommodatingthe stud and for preventing flexing of the tube where the stud islocated.

The end of the shank 30 is engaged by an am 33 which has a curved end 34that extends through one end of the tube and is secured as by welding 35to the adjacent sidewall of the container 22. The other end of the arm33 extends beyond the other end of the tube and is engaged by a link 36.

The link 36 is essentially U-shaped and has one leg thereof secured asby welding 37 to the sidewall of the container while its other end isformed with a notch 38 into which the end of the arm 33 is fitted.

It will be appreciated that the arm 33 is channel shaped in crosssection except for the arcuate end 34 to be substantially rigid betweenits engagement with the link 36 and the stud 28 but yet the curvedportion 34 permits it to flex easily. The link 36 is a flat strip ofmetal bent into a U-shape to have a round corner 39 which provides forflexing while the other leg 40 has its junction with the bight portionmade relatively rigid by reason of it being sharply bent. Actuatingforce is thus transmitted to the arm 33 through the length of the leg 40which is rigid in the direction in which the force is transmitted butyet is capable of easy flexing by the comer 39.

lf desired, the bight portion of the link 36 may be formed with anembossed upstanding dot 41 where the actuating force may be appiied andadditionally the bight portion may be formed with stamped ridges toprovide additional rigidity if needed.

With the above construction, a downward actuating force exerted on thedot 41 causes a downward movement of the leg 40 and according pivotalmovement of the arm 33 to effect radial distortion of the tube to enableinward movement of the stud 28 and a consequent actuation of the blade15. Upon removal of the force the arm and link will return to theirsolid line position which permits the tube 25 to also return to itsnondistorted position removing all force on the blade so that it mayreturn to its normal solid line position.

It will be understood that the movement of the link 36 effects flexingat the comer 39 while movement of the arm 33 is accommodated by flexingin the curved end 34. If an overtravel movement is applied to the link36, the arm 33 will move downwardly until it abuts the end of the tubeadjacent the notch 38 and subsequent actuating movement will be absorbedin the bight portion of the link 36. Thus substantial overtravel motionis accommodated by the actuator without permanently distorting eitherthe arm or link or being applied to the contact blade.

Shown in H6. 3 is a modification of the present invention in which thereis provided a plug 42 for closing the opening in the sidewall of thecontainer. The plug supports the curved end 34 of the arm 33 as forexample by welding at 43. Thus in this embodiment only one end tube isopen. If desired, the sidewali of the container could be utilized inplace of the plug. it will be understood that while a specific type ofswitch has been disclosed, other types of switches requiring physicaldisplacement for actuation may be employed if desired.

It will accordingly be appreciated that there has been disclosed anhermetically sealed electrical switch switch has an actuator fortransmitting an actuating motion to the switch through a radiallydistortable tube. The actuator includes an arm having a flexible endportion secured to the container and a free end portion which is engagedby a leg of a Ushaped link with the other endof the link being securedto the container. As the portions of the actuator which transmit motionto the switch are essentially rigid in the direction of motion and asthey have flexible portions for accommodating the movement, the actuatorresists physical deformation and accordingly maintains its mechanicaloperating characteristics over a wide range of movement.

Variations and modifications may be made within the scope of theinvention and portions of the improvements may be used without others.

lclaim:

1. In an hermetically sealed electrical switch having a membermechanically movable from one position to another to provide anelectrical signal and an hermetically sealed container enclosing saidswitch and including a radially distortable tube for transmittingmechanical movement through the container to the movable member, theimprovement comprising an actuator having an arm and a link, said armhaving a flexible end portion secured to the container and a rigidportion extending within the tube to engage the tube, said link having aflexible end portion secured on the container and a rigid portion withthe rigid portion of the arm engaged by the rigid portion of the linkand in which an actuating movement applied to the link is transmitted bythe rigid portions to the tube to effect distortion thereof to causeactuation of the switch.

2. The invention as defined in claim 1 in which the link is formed tohave a somewhat U-shape, and in which the flexible end portion includesone leg and a curved junction with the bight portion.

3. The invention as defined in claim 2 in which the rigid portion of thelink includes the other leg with a relatively rigid junction between theother leg and the bight portion and in which the actuating movement isapplied to the bi ht portion.

4. The invention as defined in claim 1 in which t e rigid portion of thearm is straight and substantially channel shape in section, and in whichsaid rigid portion extends out of one end of the tube to be engaged bythe rigid portion of the link and to have the tube limit movement of thearm.

5. The invention as defined in claim 4 in which the flexible portion ofthe arm is curved and extends out the other end of the tube to besecured to the sidewall of the container exteriorly of the tube.

6. The invention as defined in claim 4 in which the flexible portion ofthe arm is curved and is secured within the tube to the container.

7. The invention as defined in claim I in which the tube is annularlycorrugated substantially throughout its length but has a cylindricalportion aligned with the movable member, a stud secured in thecylindrical portion having a head positioned within the container fortransmitting motion to the movable member and a shank extending into thetube and in which the rigid portion of the arm engages the end of theshank.

1. In an hermetically sealed electrical switch having a membermechanically movable from one position to another to provide anelectrical signal and an hermetically sealed container enclosing saidswitch and including a radially distortable tube for transmittingmechanical movement through the container to the movable member, theimprovement comprising an actuator having an arm and a link, said armhaving a flexible end portion secured to the container and a rigidportion extending within the tube to engage the tube, said link having aflexible end portion secured on the container and a rigid portion withthe rigid portion of the arm engaged by the rigid portion of the linkand in which an actuating movement applied to the link is transmitted bythe rigid portions to the tube to effect distortion thereof to causeactuation of the switch.
 2. The invention as defined in claim 1 in whichthe link is formed to have a somewhat U-shape, and in which the flexibleend portion includes one leg and a curved junction with the bightportion.
 3. The invention as defined in claim 2 in which the rigidportion of the link includes the other leg with a relatively rigidjunction between the other leg and the bight portion and in which theactuating movement is applied to the bight portion.
 4. The invention asdefined in claim 1 in which the rigid portion of the arm is straight andsubstantially channel shape in section, and in which said rigid portionextends out of one end of the tube to be engaged by the rigid portion ofthe link and to have the tube limit movement of the arm.
 5. Theinvention as defined in claim 4 in which the flexible portion of the armis curved and extends out the other end of the tube to be secured to thesidewall of the container exterially of the tube.
 6. The invention asdefined in claim 4 in which the flexible portion of the arm is curvedand is secured within the tube to the container.
 7. The invention asdefined in claim 1 in which the tube is annularly corrugatedsubstantially throughout its length but has a cylindrical portionaligned with the movable member, a stud secured in the cylindricalportion having a head positioned within the container for transmittingmotion to the movable member and a shank extending into the tube and inwhich the rigid portion of the arm engages the end of the shank.